Photographic flashlamp unit having control structure on base

ABSTRACT

A multilamp flash unit or flashcube having a base upon which is supported a plurality of percussively-ignitable flashlamps, each having a primer tube depending therefrom, and a plurality of preenergized striker springs individually releasable to fire a respective one of the flashlamps by impact against its primer tube. The base includes a plurality of bores, into which the primer tubes are inserted for supporting the flashlamps, and a plurality of apertures, each adjacent a respective striker spring. The unit is usable on a camera having a mechanical actuating member that sequentially is movable into the unit via the apertures, upon indexing of the unit, to release successive striker springs and thereby fire successive flashlamps in the unit. A control ramp is located between each aperture and bore in the flashcube base for guiding the travel of each striker subsequent to its release to assure reliable firing of the respective flashlamp.

United States Patent [191 Shaffer PHOTOGRAPHIC FLASHLAMP UNIT HAVING CONTROL STRUCTURE ON BASE Inventor: John W. Shaffer, Williamsport, Pa.

Assignee: GTE Sylvania Incorporated, Danvers, Mass.

Filed: Dec. 23, 1971 Appl. No.: 211,553

[52] US. Cl. ..43l/93, 95/11 L [51] Int. Cl ..F21k 5/02 [58] Field of Search ..95/11 L; 431/92, 431/93, 94, 95

[56] References Cited UNITED STATES PATENTS 3,677,156 7/1972 Ettischer ..95/1I L 3,602,618 8/1971 Michatek ..43l/93 May 1, 1973 Primary Examiner-Carroll B. Dority, Jr. AtzorneyNorinan J. OMalley et a1.

[ 5 7] ABSTRACT A multilamp flash unit or flashcube having a base upon which is supported a plurality of percussively-ignitable flashlamps, each having a primer tube depending therefrom, and a plurality of preenergized striker springs individually releasable to tire a respective one of the flashlamps by impact against its primer tube. The base includes a plurality of bores, into which the primer tubes are inserted for supporting the flashlamps, and a plurality of apertures, each adjacent a respective striker spring. The unit is usable on a camera having a mechanical actuating member that sequentially is movable into the unit via the apertures, upon indexing of the unit, to release successive striker springs and thereby fire successive flashlamps in the unit. A control ramp is located between each aperture and bore in the flashcube base for guiding the travel of each striker subsequent to its release to assure reliable firing of the respective flashlamp.

10 Claims, 7 Drawing Figures Patented May 1, 1973 2 Sheets-Sheet l Patented May 1, 1973 3,730,669

2 Sheets-Sheet 2 IFIG.4

PHOTOGRAPHIC FLASHLAMP UNIT HAVING CONTROL STRUCTURE ON BASE BACKGROUND OF THE INVENTION This invention relates to photographic flashlamp units and, more particularly, to multilamp flash units, such as flashcubes, having lamps of the percussive primer type and the means employed to fire them.

The structure of a commercially available percussive-type photoflash lamp is illustrated in FIG. 1. It comprises a length of glass tubing defining an hermetically sealed lamp envelope 2 constricted at one end to define an exhaust tip 4 and shaped to define a seal 6 about primer 8 at the other end thereof. The primer 8 comprises a metal tube 10, a wire anvil l2 coaxially disposed therein, and a band of fulminating material 14 coated on the wire anvil intermediate its ends. A combustible, such as filamentary zirconium l6, and a combustion-supporting gas such as oxygen are disposed within the lamp envelope. The outer surface of the envelope 2 is covered with a suitable protective lacquer coating (not shown), such as cellulose acetate, to render the glass tube substantially shatterproof.

The lamp is mechanically fired by the impact of a striker against primer tube 10. The striker indents the thin walled tube 10 to thereby contact and ignite the fulminating material 14 whereby it deflagrates up through the tube to ignite combustible 16 disposed within the lamp envelope. A refractory bead 30, fused to the wire anvil 12 just above the inner mouth of the primer tube 10, eliminates burnthroughs and functions as a deflector to deflect and control the ejection of hot particles of fulminating material from the primer tube.

In order to provide high lamp reliability at realistic low striker impact energies, a very sensitive composition of fulminating material is required. Hence, any rubbingor pinching of the band of fulminating material 14 must be avoided if the lamp is to withstand normal shipping and handling. Accordingly, as shown in the enlarged detail view of FIG. 2, the primer assembly of the lamp is specifically designed to avoid accidental firing. More specifically, wire anvil 12 is provided with a proturberance, or head, 20 at the end thereof which is disposed within the primer tube 10. Further, a first set of diametrically disposed protuberances 22 are provided intermediate the ends of anvil l2, and a second set of diametrically disposed protuberances 24 are located above the first set of protuberances. To provide the desired coaxial centering of the anvil within tube 10, the set of protuberances 24 are located so as to lie in a plane substantially at right angles with respect to the plane in which the set of protuberances 22 lie. A crimp 28 in the metal tube on or about head 20 positively anchors wire 12, and the protuberance s 22 and 24 stabilize it within the primer tube 10. The fulminating material 14 may be dip applied to the wire anvil below the protuberances 22 and subsequently removed from the lower portion of the anvil including head 20 so that the entire body of fulminating material is located between the head 20 and the protuberances 22. A spacing y is provided between band 14 and head 20 so as to leave an axial clearance between the lower boundary 26 of the fulminating material and the upper inside surface of crimp 28. The diameter of the head 20 and the diameter of a circumscribed circle about the protuberances 22 and 24 are each larger than the diameter of the coating of fulminating material 14 so as to also provide a radial clearance X between the fulminating material and the the inner wall of primer tube 10. Clearances X and Y must be sufficient to prevent contact between the fulminating material 14 and the inner wall of the metal tube 10 even when the lamp is vibrated such that the anvil moves slightly relative to the tube in which it is mounted.

One embodiment of a multilamp flash unit of the type with which the present invention is concerned is illustrated in FIG. 3. This unit, which may be referred to as a percussive flashcube 32, comprises a substantially rectangular base 34 along each side of which is arranged a percussive flashlamp 36, of the type described. Each lamp 36 is provided with a respective reflector 38 and a respective preenergized striker spring 42, and the assemblage of lamps, striker springs and reflectors is enclosed in a transparent cover 40 secured to the base 34.

A single lamp-striker spring assembly, as mounted on a prior art type of base, is more clearly shown in the simplified enlarged view of FIG. 4. The flashlamp 36 is supported on the base by means of a bore 44 into which the primer tube 10 is inserted. Spring 42 is a folded torsion device typically formed from 0.021 inch music wire about 2.5 inches long. The wire is shaped to form a hairpin torsional section having segments 46 and 48 and a bight 50. The end portion of segment 46 is shaped to define a stationary supporting foot 52 (not shown in this view), the tip of which is shaped to define a catch 54. The end portion of segment 48 is shaped to define a striker 56, which when the spring is preenergized, or cocked, as shown, crosses over the supporting foot 52 and is restrained by catch 54. The stationary supporting foot is seated in an elongated slot formed in the base on or near a diagonal thereof, said slot being sufficiently shallow so that the catch 54 formed on the free end of foot 52 will project a relatively substantial distance above the, plane of the upper surface of the base.

Displacement of the cocked striker 56 to release it from the catch 54 and thus permit it to strike the primer tube 10 andfire the lamp, is effected by a suitable actuating member 58 moving up through an aperture 60 provided therefor in the base. When the member 58 pushes the striker 56 upwardly a distance sufficient to clear the top of the catch 54, the striker swings clockwise, as shown by the arrow, and hits and indents the impact sensitive primer tube 10 at high velocity to cause deflagration of the fulminating material located therein and thus ignite the combustible foil 16.

The lower surface of the flashcube base is provided with a suitable center post or the like (not shown) for mounting on apparatus such as a camera and providing a means whereby the flashcube :may be rotated after a lamp has been flashed so that another lamp may be advanced to the firing position. Hence, the actuating member 58 may be part of a camera mechanism designed to enable a photographer to flash a lamp in synchronization with the tripping of the camera shutter to take a picture. The mechanical power input to the actuating member from the shutter responsive triggering mechanism is quite limited in practical camera designs, and a minimum upward travel for the member 58 is desirable. One type of camera mechanism suitable for use with percussive flashcubes is described in U.S. Pat. No. 3,602,618.

Referring again to the flash lamp primer (FIG. 2), the location of the lower edge 26 of the band of fulminating material 14 is subject to certain manufacturing tolerances which are essentially impossible to eliminate with automated equipment. In order to prevent contact of the fulminating material 14 with the tube crimp 28, as discussed hereinbefore, it is desirable to provide a large spacing Y between the anvil head 20 and the band 14 of fulminating material. This helps assure freedom from inadvertent lamp flashing. The spring striker 56, however, must indent tube so that the resulting impact pinches the fulminating material 14 between the tube 10 and anvil 12. If the striker indents the tube at or below the lower boundary 26 of the fulminating material, the lamp will most probably fail to flash. Consequently, any upward movement of the lamp tubel0 out of the bore 44 in the flashcube base, as could occur due to vibration during manufacture, handling or use, can result in decreased product reliability.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide an improved flash unit of the type containing a percussive flashlamp and a preenergized striker for firing the lamp.

A principal object of the invention is to provide a percussive multilamp flash unit that maintains high reliability after severe handling, and which has substantially less likelihood of inadvertent lamp flashing during manufacture, handling and use.

Another object is to provide a percussive flashcube for cameras which provides the above-mentioned objects while at the same time retaining the desired minimum travel distance for the camera actuating member.

These and other objects, advantages and features are attained, in accordance with the principles of this invention, by providing a ramp on the upper surface of the flashcube base between each flashlamp and the aperture through which the camera actuating member passes to release the overlying striker spring. The ramp substantially defines an inclined plane rising toward the primer tube of the flashlamp and is adapted to be slidably engaged by the striker during its travel subsequent to release. In this manner, the moving striker is guided to cause impact of the fulminating material sufflciently above its lower boundary to reliably fire the flashlamp. This type of control structure on the flashcube base is particularly advantageous in that it simultaneously permits both the desired low initial striker position, with minimized travel for the camera actuating member, and a sufficient clearance between the primer tube crimp and the fulminating material to reduce the probability of inadvertent lamp flashing.

BRIEF DESCRIPTION OF THE DRAWINGS This invention will be more fully described hereinafter in conjunction with the accompanying drawings in which:

FIG. 1 is an elevational view partly in section of a percussive type photoflash lamp to which previous reference has been made;

FIG. 2 is a fragmentary detail on an enlarged scale of the primer of the lamp of FIG. 1 to which previous reference has been made;

FIG. 3 is a simplified perspective view of a percussive flashcube with a portion broken away for clarity and to which previous reference has been made;

FIG. 4 is an elevational cross-section providing a sim plified illustration on an enlarged scale of a single lampfiring spring assembly mounted on a prior art type of flashcube base, and to which previous reference has been made;

FIG. 5 is an elevational cross-section providing a simplified illustration on an enlarged scale of a single lampfiring spring assembly mounted on a flashcube base in accordance with the present invention;

FIG. 6 is a fragmentary view on an enlarged scale ofa single lamp-firing spring assembly of the flashcube of FIG. 3 embodying the principles of this invention; and

FIG. 7 is a plan view of the base of the flashcube of FIG. 3 in accordance with the invention with the several spring members shown in full and the several flashlamps associated therewith shown in phantom.

DESCRIPTION OF PREFERRED EMBODIMENT The present invention may be embodied in a percus sive flashcube of the type generally shown in FIG. 3 by means of the base structure illustrated with more particularity in FIGS. 5-7. The simplified view of FIG. 5 is somewhat similar to FIG. 4 in that it shows a percussive flashlamp 36 and a torsion spring 42, both of the type described hereinbefore, mounted on a percussive flashcube base. In accordance with the present invention, however, the base 34 of FIG. 5 includes a ramp 62 on its upper surface between the aperture 64, through which actuating member 58 passes, and the bore 66 in which the primer tube 10 of lamp 36 is inserted. The ramp 62 may be molded as an integral part of the base 34 and is formed to substantially define an inclined plane rising toward the primer tube 10 of the flashlamp. Thus, whereas in FIG. 4 the upper surface of the prior art flashcube base proximate bore 44 and aperture 60 is coplanar, FIG. 5 shows the upper surface of base 34 proximate bore 66 elevated from the upper surface of base 34 proximate aperture 64 by the rise of the ramp 62. In this manner, the depth of the bore 66 is made sufficient to dispose the lower boundary 26 of the fulminating material in primer 8 (FIG. 2) well within the bore when primer tube 10 is fully inserted therein. As a result of this configuration, ramp 62 is adapted to be slidably engaged by the striker 56 during its travel, subsequent to release from catch 54 by the upward movement of actuating member 58, to thereby guide the moving striker 56 toward impact against primer tube 10 in a manner operative to reliably fire the flashlamp 36.

During the development of the percussive flashcube, it was observed that if the tip of the high velocity striker 56 made any contact with other objects during its travel, such as scuffing an inside face of the flashcube cover 40, the kinetic energy of the firing spring and, consequently, the reliability of lamp flashing were sub stantially reduced. It was quite surprising, therefore, to find that the provision of a ramp 62 on the upper surface of the percussive flashcube base raises the primer tube indent height without either adversely affecting lamp reliability or causing the striker to bounce too high and hit, for example, the glass envelope of the lamp. These favorable results are probably due to the fact that the ramp slidably engages the smooth underside of the striker wire 56, as opposed to the cusp of the striker tip; also, the velocity is greater at the tip of the striker than near its fulcrum, and the leverage ratio and force characteristics differ. i

The primer tube cannot be moved farther downward in the prior art flashcube base. Similarly, the size of the anvil head (FIG. 2) and the elevation of crimp 28 above the bottom of the tube 10 have been minimized. The only alternative way of increasing clearance between tube crimp and fulminating material to reduce inadvertent flashing, while at the same time giving a sufficient minimum spring strike height on the primer tube to assure reliable operation, would be to increase the overall base thickness and initial height of the spring striker. As pointed out previously, mechanical considerations of the camera actuating member drive mechanism contraindicates such a change in the percussive flashcube-to-camera interface dimensions.

Accordingly, the ramp control structure of the invention is particularly advantageous in that it permits both the desired low initial striker position with minimized travel for the camera actuating member 58 and a sufficient clearance between the primer tube crimp 28 and the lower boundary 26 of the fulminating material (FIG. 2) to reduce the probability of inadvertent lamp flashing.

A more detailed illustration of the percussive flashcube base structure according to the invention is shown in FIGS. 6 and 7. Referring first to FIG. 6 flash lamp 36 is supported on the base 34 by means of its primer tube 10 being fully inserted in bore 66. Also mounted on the base 34 is a folded torsion spring 42 of the type described hereinbefore. Again, the spring includes the pair of segments 46 and 48 joined by bight 50, with the end portion of segment 46 being shaped to define-the stationary supporting foot 52, the tip of which is shaped to define catch 54. Portions of the foot 52 and catch 54 are hidden in FIG. 6. Projecting from the lower end of segment 48 is the striker 56 which, when the spring is preenergized, or cocked, as shown, crosses the supporting foot 52 and is restrained by the catch 54. The stationary supporting foot is seated in an elongated slot formed in the base 34 on or near a diagonal thereof, the slot being sufficiently shallow to permit catch 54 to project above the upper surface of the base 34.

Initially the striker 56 may be formed at an angle of about 90 to the stationary supporting foot 52, although the angle through which the striker is rotated to position it behond catch 54, as shown, may be of any value that does not cause overstressing of the wire. A center post 68 on the upper surface of the base 34 provides a suitable bearing surface for the heel of the striker during cooking, and it also aids in preventing accidental displacement of the spring 42 sufficient to free the striker from the catch some time after cocking and before firing is intended.

As previously described, striker 56 overlies and is adjacent to the aperture 64 whereby it is accessible to be released by the actuating member 58. In this instance, aperture 64 comprises a slot having a circumferentially arcuate shape. In accordance with the invention, the ramp 62 begins at or near the end of slot 64 nearest to horizontal flat area may be provided about the bore.

66 to facilitate insertion of the primer tube 10 into the bore. Thus, the perimeter of aperture 64 in the upper surface of the base 34 lies in a first horizontal plane, while the upper surface of base 34 proximate bore 66 is substantially flat and lies in a second horizontal plane elevated from the first horizontal plane, with the ramp 62 rising from the first horizontal plane to the second horizontal plane. The total elevation Z of the ramp 64 may vary from about 0.001 inch to about 0.040 inch, if desired; I prefer to use a ramp that rises 0.010 inch above the rest position of the striker 56, which is the upper terminating surface of slot 64.

The bottom or lower face of the base 34 is provided with a suitable center post or the like (not shown) for mounting on a camera and providing a means whereby the flashcube may be rotated after the lamp has been flashed so that another lamp may be advanced to the firing position. As illustrated in FIG. 7, each of the four flashlamps 36 is provided with its own firing mechanism as shown in detail in FIGS. 5 and 6 and described above. The hairpin torsional sections of the springs are clustered in the space behind thereflectors 38 (FIG. 3), with a clearance being provided alongthe.

lower edges of these reflectors to permit free operation of the strikers. The four sets of bores 66, ramps 62 and apertures 64 are symmetrically arranged in a circular pattern about the center of the upper surface of base 34, with each of the apertures 64 comprising a slot hav ing a circumferentially arcuate shape, and each of the ramps 62 having a circumferentially arcuate shape.

As previously described, displacement of each cocked striker 56, to release itfrom catch 54 and thus permit it to strike a respective primer tube 10 and fire the respective lamp, is effected by the actuating member 58 moving up through the slot 64. As noted before, member 58. may be actuated by and in synchronism with the shutter mechanism of a camera upon which the flashcube is mounted. When member 58 pushes the striker 56 upwardly a distance sufficient to clear the top of catch 54, the striker swings clockwise in a circular are as shown by the arrows in FIGS. 6-7. In this instance, however, the control ramp 62, by virtue of its position, incline and arcuate shape, engages the underside of the moving striker to guide its path of travel whereby the striker indents the impactsensitlve primer tube 10 so as to reliably pinch the band of fulminating material 14 well above its lower boundary 26 (FIG. 2). This high velocity impact causes deflag'ration of the fulminating material up through the tube 10 to ignite the combustible foil 16.

In summary, the base control ramps 62 effectively raise the minimum height on the lamp primer tube 10 that the striker 56 indents upon camera activation, while at the same time permitting a desirable low initial position for the spring striker 56. Such a base configuration permits increased clearance between the primer tube crimp 28 (FIG. 2) and the lower boundary 26 of the fulminating material, thereby giving a lower probability of inadvertent lamp flashes during manufacture, handling and use of the product. The control ramps also increase the reliability of lamp operation in the event of upward lamp displacement in the flashcube base as may occur, for example, when the cube is dropped. A further advantage is that such lamp movement is less liable to occur because the increased base material about the primer tube, as described herein, provides a better grip, on the tube by the percussive flashcube base.

Although the invention has been described with respect to a specific embodiment, it will be appreciated that modifications and changes may be made by those skilled in the art without departing from the true spirit and scope of the invention. For example, while the invention has been described with respect to flashcubes, ti will be understood the use of a ramp control structure to attain the aforementioned advantages may also be employed with other types of flash units, such as single lamp units, linear arrays of lamps, and multilevel or bidirectional arrays of lamps.

What I claim is:

1. Control structure in a flashlamp-containing unit; said unit being receivable on apparatus having a mechanical actuating member for firing a flashlamp in said unit; said unit including a base having an upper surface for supporting said flashlamp and for supporting a preenergized striker releasable to fire said flashlamp; said base further having means defining an aperture adjacent said striker and through which said striker is accessible to be released by said actuating member to fire said flashlamp; the control structure comprising:

a ramp on the upper surface of said base between said aperture and said flashlamp, said ramp substantially defining an inclined plane rising toward said flashlamp, and said ramp being adapted to be slidably engaged by said striker during the travel of said striker subsequent to its release whereby the moving striker is guided to reliably fire said flashlamp.

2. The control structure of claim 1 wherein said flashlamp is a percussively-ignitable lamp having a primer tube depending therefrom, said base further has means defining a bore in the upper surface thereof for receiving the primer tube of said lamp, the free end of said primer tube being inserted in said bore to thereby support said'flashlamp on said base, and said ramp is disposed between said aperture and said bore.

3. The control structure of claim 2 wherein the perimeter of said aperture in the upper surface of said base lies in a first horizontal plane, the upper surface of said base proximate said bore is substantially flat and lies in a second horizontal plane elevated from said first horizontal plane, and said ramp rises from said first horizontal plane to said second horizontal plane, said flat surface proximate said bore being adapted to facilitate insertion of the primer tube of said lamp into said bore during assembly. I

4. The control structure of claim 2 wherein said flashlamp comprises: an hermetically sealed, lighttransmitting envelope; a quantity of filamentary combustible material located within said envelope; a combustion-supporting gas in said envelope; and a primer secured to and extending from the lower end of said envelope and in communication therewith, said primer including said tube sealed in said lower end of said envelope and having an exposed segment outside said envelope, a wire anvil located within said tube, and a body of fulminating material located on said wire anvil intermediate its ends and on that segment of said wire anvil located in said exposed segment of said tube but spaced from the inside wall thereof, the lower boundary of said fulminating material being spaced from the lower end of said wire anvil; and wherein the upper surface of said base proximate said bore is elevated from the upper surface of said base proximate said aperture by the rise of said ramp whereby the depth of said bore is sufficient to dispose said lower boundary of said fulminating material within said bore when said primer tube is fully inserted therein.

5. A base for a multilamp flash unit; said unit including a plurality of 'percussively-ignitable flashlamps each having a primer tube depending therefrom, and a plurality of preenergized strikers individually releasable to fire a respective one of said flashlamps; said unit further being receivable on apparatus having a mechanical actuating member operable to release one of said strikers to fire its respective flashlamp; the base comprising:

means defining first and second axially spaced surfaces;

means defining a plurality of bores in said second surface for respectively receiving the primer tubes of said flashlamps to provide support therefor;

means in said second surface for supporting said preenergized strikers;

means defining an aperture in said base adjacent each striker and through which aperture the respective striker is accessible to be released by said actuating member to fire its respective flashlamp; and,

a ramp on said second surface between each bore and aperture, said ramp substantially defining an inclined plane rising toward the respective bore, and said ramp being adapted to be slidably engaged by a respective one of said strikers during the travel of the striker subsequent to its release.

6. The base of claim 5 wherein a plurality of said bores, ramps and apertures are symmetrically arranged in a circular pattern about the center of said second surface, each of said apertures is a slot having a circumferentially arcuate shape, and each of said ramps has a circumferentially arcuate shape.

7. The base of claim 6 wherein the elevation of said ramp lies in the range of about 0.001 inch to about 0.040 inch.

8. A multilamp flash unit receivable on apparatus including an actuating member; the unit comprising:

a substantially-planar base defining upper and lower spaced surfaces and an aperture through the base; plurality of flashlamp devices supported on the upper surface of said base, each device including a percussively-ignitable flashlamp and a preenergized firing spring individually releasable to impact against and fire a respective flashlamp, said firing spring including a striker portion located closely adjacent said upper surface and over said aperture to be released by said actuating member to fire the flashlamp; and,

a striker guiding ramp on the upper surface of said base between each aperture and flashlamp, said ramp substantially defining an inclined plane rising toward a respective flashlamp, and said ramp being adapted to be slidably engaged by the striker portion of a respective one of said firing springs during the travel of said striker portion subsequent to its release whereby the moving striker portion is guided to reliably fire said respective flashlamp.

9. The unit of claim 8 wherein each of said flashlamps comprises: an hermetically sealed, lighttransmitting envelope; a quantity of filamentary combustible material located within said envelope; a combustion-supporting gas in said envelope; and a primer secured to and extending from the lower end of said envelope and in communication therewith, said primer including a tube sealed in said lower end of said envelope and having an exposed segment outside said envelope, a wire anvil located within said tube, and a body of fulminating material located on said wire anvil intermediate its ends and on that segment of said wire anvil located in said exposed segment of said tube but spaced from the inside wall thereof, the lower boundary of said fulminatirig material being spaced from the lower end of said wire anvil; and wherein sd base further has a plurality of bores in the upper surface thereof each for receiving the primer tube of a respective one of said lamps to provide support therefore, each striker guiding ramp is disposed between a respective aperture and bore; and, the upper surface of said base proximate each bore is elevated from the upper surface of said base proximate a respective aperture by the rise of the respective ramp therebetween whereby the depth of said bore is sufficient to dispose said lower boundary of said fulminating material within the bore when said primer tube is fully inserted therein, the striker portion of each firing spring being releasable to impact against the primer tube of its respective flashlamp and thereby fire said flashlamp.

10. The unit of claim 9 wherein each of said firing springs is a folded torsional spring comprising a substantially hairpin torsional section having two segments joined by a bight, said striker portion projecting from one of said segments, a supporting toot projecting from the other of said segments and fixedly mounted on the upper surface of said base, and a catch formed at the tip of said foot, said striker portion crossing said foot with said catch restraining said striker portion in a cocked condition. 

1. Control structure in a flashlamp-containing unit; said unit being receivable on apparatus having a mechanical actuating member for firing a flashlamp in said unit; said unit including a base having an upper surface for supporting said flashlamp and for supporting a preenergized striker releasable to fire said flashlamp; said base further having means defining an aperture adjacent said striker and through which said striker is accessible to be released by said actuating member to fire said flashlamp; the control structure comprising: a ramp on the upper surface of said base between said aperture and said flashlamp, said ramp substantially defining an inclined plane rising toward said flashlamp, and said ramp being adapted to be slidably engaged by said striker during the travel of said striker subsequent to its release whereby the moving striker is guided to reliably fire said flashlamp.
 2. The control structure of claim 1 wherein said flashlamp is a percussively-ignitable lamp having a primer tube depending therefrom, said base further has means defining a bore in the upper surface thereof for receiving the primer tube of said lamp, the free end of said primer tube being inserted in said bore to thereby support said flashlamp on said base, and said ramp is disposed between said aperture and said bore.
 3. The control structure of claim 2 wherein the perimeter of said aperture in the upper sUrface of said base lies in a first horizontal plane, the upper surface of said base proximate said bore is substantially flat and lies in a second horizontal plane elevated from said first horizontal plane, and said ramp rises from said first horizontal plane to said second horizontal plane, said flat surface proximate said bore being adapted to facilitate insertion of the primer tube of said lamp into said bore during assembly.
 4. The control structure of claim 2 wherein said flashlamp comprises: an hermetically sealed, light-transmitting envelope; a quantity of filamentary combustible material located within said envelope; a combustion-supporting gas in said envelope; and a primer secured to and extending from the lower end of said envelope and in communication therewith, said primer including said tube sealed in said lower end of said envelope and having an exposed segment outside said envelope, a wire anvil located within said tube, and a body of fulminating material located on said wire anvil intermediate its ends and on that segment of said wire anvil located in said exposed segment of said tube but spaced from the inside wall thereof, the lower boundary of said fulminating material being spaced from the lower end of said wire anvil; and wherein the upper surface of said base proximate said bore is elevated from the upper surface of said base proximate said aperture by the rise of said ramp whereby the depth of said bore is sufficient to dispose said lower boundary of said fulminating material within said bore when said primer tube is fully inserted therein.
 5. A base for a multilamp flash unit; said unit including a plurality of percussively-ignitable flashlamps each having a primer tube depending therefrom, and a plurality of preenergized strikers individually releasable to fire a respective one of said flashlamps; said unit further being receivable on apparatus having a mechanical actuating member operable to release one of said strikers to fire its respective flashlamp; the base comprising: means defining first and second axially spaced surfaces; means defining a plurality of bores in said second surface for respectively receiving the primer tubes of said flashlamps to provide support therefor; means in said second surface for supporting said preenergized strikers; means defining an aperture in said base adjacent each striker and through which aperture the respective striker is accessible to be released by said actuating member to fire its respective flashlamp; and, a ramp on said second surface between each bore and aperture, said ramp substantially defining an inclined plane rising toward the respective bore, and said ramp being adapted to be slidably engaged by a respective one of said strikers during the travel of the striker subsequent to its release.
 6. The base of claim 5 wherein a plurality of said bores, ramps and apertures are symmetrically arranged in a circular pattern about the center of said second surface, each of said apertures is a slot having a circumferentially arcuate shape, and each of said ramps has a circumferentially arcuate shape.
 7. The base of claim 6 wherein the elevation of said ramp lies in the range of about 0.001 inch to about 0.040 inch.
 8. A multilamp flash unit receivable on apparatus including an actuating member; the unit comprising: a substantially planar base defining upper and lower spaced surfaces and an aperture through the base; a plurality of flashlamp devices supported on the upper surface of said base, each device including a percussively-ignitable flashlamp and a preenergized firing spring individually releasable to impact against and fire a respective flashlamp, said firing spring including a striker portion located closely adjacent said upper surface and over said aperture to be released by said actuating member to fire the flashlamp; and, a striker guiding ramp on the upper surface of said base between each aperture and flashlamp, said ramp substantially dEfining an inclined plane rising toward a respective flashlamp, and said ramp being adapted to be slidably engaged by the striker portion of a respective one of said firing springs during the travel of said striker portion subsequent to its release whereby the moving striker portion is guided to reliably fire said respective flashlamp.
 9. The unit of claim 8 wherein each of said flashlamps comprises: an hermetically sealed, light-transmitting envelope; a quantity of filamentary combustible material located within said envelope; a combustion-supporting gas in said envelope; and a primer secured to and extending from the lower end of said envelope and in communication therewith, said primer including a tube sealed in said lower end of said envelope and having an exposed segment outside said envelope, a wire anvil located within said tube, and a body of fulminating material located on said wire anvil intermediate its ends and on that segment of said wire anvil located in said exposed segment of said tube but spaced from the inside wall thereof, the lower boundary of said fulminating material being spaced from the lower end of said wire anvil; and wherein sd base further has a plurality of bores in the upper surface thereof each for receiving the primer tube of a respective one of said lamps to provide support therefore, each striker guiding ramp is disposed between a respective aperture and bore; and, the upper surface of said base proximate each bore is elevated from the upper surface of said base proximate a respective aperture by the rise of the respective ramp therebetween whereby the depth of said bore is sufficient to dispose said lower boundary of said fulminating material within the bore when said primer tube is fully inserted therein, the striker portion of each firing spring being releasable to impact against the primer tube of its respective flashlamp and thereby fire said flashlamp.
 10. The unit of claim 9 wherein each of said firing springs is a folded torsional spring comprising a substantially hairpin torsional section having two segments joined by a bight, said striker portion projecting from one of said segments, a supporting foot projecting from the other of said segments and fixedly mounted on the upper surface of said base, and a catch formed at the tip of said foot, said striker portion crossing said foot with said catch restraining said striker portion in a cocked condition. 